Cellulosic article



Patented Feb. 28, 1939 UNITED STATES OELLULOSIO ARTICLE Manfred Keller,Syosset, N. Y., assignor, by memo assignments, to E. I. du Pont deNemours' a Company, Wilmington,- Del., a corporation of Delaware NoDrawing. Application December 8, 1935, Serial No. 53,272

2 Claims.

This invention relates to sails to be used for sail-boats and the like,and it pertains particularly to the use of high tenacity rayon in themanufacture of sail cloth. Sails for yachts and other sailing vesselscomprise heavy cotton cloth, such as cotton duck. It is the aim of sailmanufacturers to produce sails which will exhibit a long, useful lifeunder the severe strains to which the sails are subjected. The necessityfor comparatively frequent repair and replacement of cotton sailsindicates a definite need of improvement in this art.

By way of indicating one of the undesirable features of cotton sails, itis a known fact that cotton sails stretch out of shape and assume apermanent increase'in size, due to the severe strain to which sails aresubjected, and this fact, due to the loss in emciency of the sails,causes many yachtsmen to dispense with their sails long before the endof the natural life of the .cotton fabric.

It hasbeen found, in accordance with the present invention, that sailsmade from fabrics woven from high tenacity rayon overcome many of thedisadvantages incident to the use of cotton sails, and exhibit a muchlonger useful life and greater efficiency than cotton sails.

It is an object of the present invention to provide improvement'in sailconstruction.

A further object of the invention relates to the manufacture of sailcloth, having an efiiciency and useful life greatly superior to those ofcotton sail cloth.

A still further object of the invention pertains to the use of hightenacity rayon in the manufacture of sails from sail cloth.

Other objects of the invention will become ap parent hereinafter.

The objects of the present invention are accomplished in general byconstructing sails of fabric in which the warp threads, and preferablythe filler threads also, comprise high tenacity rayon. High tenacityrayon normally has a low percentage elongation. It is preferred, inaccordance with the present invention, that the high tenacity threadusedfor sail construction have a percentage elongation not in excess12%, and preferably below High tenacity, low elongation rayon threads,

adaptable for use in the present invention may be obtained by theviscose process, as described in the United States application of HaroldHenry Parker, Serial No. 676,463, filed June 19, 1933.

The following examples illustrate types of high tenacity rayon fabricssuitable for use in the manufacture of sails in accordance with thepresent invention.

Example 1.-Two hundred seventy-five depier-120 filament regeneratedcellulose thread produced by the viscose process, twisted to 7 turnsdirection opposite to the thread twist.

weighs 1 pound for 2.98 yards, having the said width of 28% inches.

Example 2.-230 denier--9G filament regenerated cellulose thread,prepared by the viscose process, having approximately the same tenacityand elongation as the thread of Example 1, but having 6 turns per inchtwist, is plied into a strand by taking two ends of the thread anddoubling with a twist of four turns per inch in a These strands are usedin both warp andfilling, and are woven with 72 warp threads to the inchand 54 filling threads to the inch, the width of the piece being 28inches. The fabric weighs 1 pound for 2.44 yards, having a widthas'stated of 28 V inches.

ated cellulose thread made by the viscose process and having the sametenacity and elongation as the thread of Example 1, the thread having 7turns per inch twist, is plied into strands by taking two ends of thethread and doubling by twisting to four turns per inch in a directionopposite to the thread twist, the thread being used as both warp andfilling threads in the fabric. The warp comprises 80 threads to the inchand the filler comprises 46 threads to the inch, the width of the fabricbeing 28 inches. The fabric weighs 1 pound'for 2 yards of fabric, havingthe said width of 28% inches.

Example 4.--275 denier-120 filament regenerated cellulose thread made bythe viscose process and having the same tenacity and elongation as thethread of Example 1, the thread having 7 turns per inch, is used as boththe warp and filling threads in the manufacture of a fabric, warp andfiller both comprising 68 threads to the inch, the fabric being 28%inches wide and of any desired length. This fabric construction isparticularly valuable since it greatly reduces the transverse stretch ofthe fabric.

Fabrics prepared in accordance with Examples 1 to 4 are preferablywaterproofed with any suitable waterproofing composition It is desiredto note, in this connection, that the waterproofed high tenacity rayonfabric dries much more rapidly than cotton fabric.

Sails are made from the sail duck fabric, prepared in accordance withthe instructions given in Examples 1 to 4, in any suitable fashion. Thesails should, be cut in sucha way as to allow for the stretching of theleech rope and in this respect, the sails are cut differently fromcotton Example 3.275 denier-F120 filament regenersails since cottonsails stretch with the leech rope and no such allowance has to be made.As a matter of fact, in the construction of cotton sails, certaindetails have to be observed to make allowance for the stretching of thesail fabric rather than for the stretching of the rope.

Various types of sails may be made from the high tenacity rayon sailfabrics described in the examples. Thus mainsails and also jib sailsmade from high tenacity rayon exhibit high emciency and durability.

There are many advantages accruing from the use of high tenacity rayonin sail cloth which indicate the greater utility of the new type of sailas compared with cotton sails. High tenacity rayon has a much greaterdry strength, than cotton thread of the same size, thereby permittingthe manufacture of sails which are lighter in weight than cotton sails,but of equal strength. Since the weight of a sail is very important andsince it is desirable to have as light a sail as possible, this featureis of great importance.

Furthermore, sails made of regenerated cellulose will not mildew to asgreat an extent as cotton sails, mildewing being found to be a veryobjectionable disadvantage of cotton sails.

Sails made of high tenacity rayon fabric additionally exhibit a muchgreater tear resistancetransversely of the fabric than sails made ofcotton fabric.

High tenacity rayon thread has a much lower wet and dry elongation thanhave cotton threads, and fabrics prepared with high tenacity rayonexhibit far less permanent stretch or growth" than do cotton fabrics,thereby retaining their shape for a much longer period of time and alsoexhibiting a longer efiicient life.

In addition, rayon sails are formed from rayon thread which is composedof continuous filaments as distinct from cotton threads which aretwisted from staple fibers. The rayon sails exhibit an absence of lint,indicating that the rayon sails will have less surface friction thancotton sails and will spill the wind more rapidly. The speed of asailboat is dependent, to a certain extent, on the rate at which thewind moves over the surface of the sail, the smoothness of the fabric,when made of rayon, being a definite advantage. In addition, the smoothsurface of rayon sail fabric, especially when used in Genoa andintermediate Jib sails, is a great advantage because in changing tack,the sail will move much more rapidly across the stays of the boat thanin the case of cotton sails.

Strong rayon sail fabric furthermore permits less wind passage throughthe fabric than in the case of comparable cotton fabrics, due to thegreater coverage of rayon fabric as compared with cotton fabrics.

While, generally speaking, various deniers can be used in constructingsail cloth, depending upon the type of boat on which the sail is to beplaced, it is usually desirable to use thread having a denier of 200, orgreater. Although the invention contemplates broadly rayon having a drytenacity at room temperature of at least 2.5 grams per denier, it ispreferred that the strength be 2.8 grams or greater.

While the examples illustrate the use of high tenacity rayon threadhaving a twist of 4 and 7 turns per inch, any suitable twist may beimparted to the thread. Likewise, when the thread is plied, any suitableply twist, in a direction which is either the same or opposite to thethread twist,

1 may be used. It may bedesired in some inamaoai stances, for example,to twist the thread from 10 to 18 turns per inch, especially in thefilling thread, when a more rigid and less easily distorted fabric ispreferred. A high ply twist may also be desirable for the same reason.

Instead of plying thread in a twisting ,operation in the mannerdescribed in Examples 2 and 3, a larger denier thread may be used in thefirst instance, thereby avoiding the plying operation. Thus, in place ofthe 230 denier thread of Example 2 and the 275 denier thread of Example3, a thread of approximately double these deniers could be used, toobtain a comparable fabric, while eliminating the operation of plyingthe thread into strands.

"High tenacity rayon or its equivalent, as used throughout thespecification and claims, signifies rayon having a tenacity, when dryand at room temperature (i. e., F.), of at least 2.5 grams per denier.

Elongation" (unless otherwise qualified), as used throughout thespecification, means percentage elongation of the dry thread at thebreaking point when tested at room temperature.

Tenacity or its equivalent (unless otherwise qualified), as usedthroughout the specification and claims, signifies (tenacity) themaximum load that can be put on the dry thread at room temperature. 1

Both tenacity and elongation of high tenacity rayon are determined bythe following test:

The thread is reeled under uniform tension in 450 meter skeins; theseskeins are conditioned for 3 hours in an atmosphere maintained at 60%relative humidity and 75 F.; the skeins are then weighed to determinethe denier which is defined as the weight in grams of 9,000 meters.

The tests for determining tenacity and elongation are made on a Sutersingle strand strength and elasticity tester with an oil plungercontrolled pull. The rate of fall of the plunger is 1 foot per minute,and the distance between the clamps is adjusted for an 18-inch length ofyarn. In making the dry test, five single strands from each of the aboveskeins are tested separately. These are clamped in the tester andstretched until the yarn breaks. Both the breaking load in grams and theper cent elongation may be read directly from scales on the machine.

Grams per denier are obtained by dividing the scale reading in grams bythe denier of the thread.

The average of 50 dry breaks on threads selected at random is consideredto be the tensile strength for any given -pound lot of yarn.

Where methods of testing other than those specifically referred toherein are used, different numerical results may be obtained, but therelative improvement over the prior art will be of the same order,regardless of the method of testing used.

Since the invention is capable of considerable modification andvariation from the details given above, any change which conforms to thespirit of the invention is intended to be included in the scope of theappended claims.

I claim:

1. Sails comprising high tenacity rayon, having an elongation not inexcess of 12%, said rayon being regenerated cellulose.

2. Sails as defined in claim 1, characterized in that the rayoncomprises thread having a denier of at least 200.

MANFREDKELIER.

